The basis of mutant phenotypes in membrane-associated traits of cultured mammalian cells will be investigated in genetic, biochemical, and immunological experiments. Human cells resistant to ouabain inhibition of plasma membrane Na/K ATPase will be examined with respect to transport properties, ouabain binding, surface antigens, expression of the traits in somatic cell hybrids, and molecular properties of the ATPase in partially purified preparations. Chinese hamster ovary (CHO) cells resistant to Concanavalin A and temperature-sensitive for growth will be examined to define alterations in surface-labelled glycoproteins and their synthesis, to characterize associated cellular properties such as adherence and response to other drugs, and to study expression of these properties in somatic cell hybrids. Other experiments will be undertaken to investigate Hela cell variants with altered susceptibility to the mutagen ethyl methane sulphonate (EMS). BIBLIOGRAPHIC REFERENCES: Baker, Raymond M. (1976). Genetic and cellular properties of ouabain-resistant mutants. In Biogenesis and Turnover of Membrane Macromolecules (ed. John S. Cook), pp. 93-103, Raven Press, New York, in press. Cifone, Maria A. and R.M. Baker (1976). Abstract: Concanavalin A-resistant temperature-sensitive CHO cells. J. Cell Biol. 70, 77a.